does anyone know of a ARM board that has
5v inputs
can run linux / windows ce
has hdmi / vga outputs
interested to learn more
Gadget999:
does anyone know of a ARM board that has5v inputs
can run linux / windows ce
has hdmi / vga outputsinterested to learn more
Is 5V inputs that important? Because you can use external IC to translate 5V to 3V3 easily (74HC125 for example).
Beaglebone black matches but it's 3v3.
AFAIK, all of the linux-capable ARMs will be low-voltage chips, in order to interface to the high density RAM chips that you need for linux on a reasonable-sized board. (DDR3 is 1.5V !)
i wanted 5 v because some of the sensors i use output 5v digital
i guess i can use them with a zener to protect the input
why can the pins not take 5v ?
why can the pins not take 5v ?
Approximately: because the design rules that let you fit a processor of that complexity on a cheap chip also cause the individual transistors to become too small to handle higher voltages.
Just use an external level shifter, for receiving signals just a simple voltage divider does the job most of the time. Some boards are even happy with a 10k resistor in series to simply limit the current on the input although I personally do not like this approach.
Only ARM chip I have ever seen with 5v tolerant inputs is the LPC1114 which is a microcontroller and certainly not linux capable.
SixSixSevenSeven:
Only ARM chip I have ever seen with 5v tolerant inputs is the LPC1114 which is a microcontroller and certainly not linux capable.
The Teensy 3.1 which uses the Freescale Cortex-M4, MK20DX256VLH7 has 5v tolerant inputs for digital pins. The analog pins that also support digital input/output, will take 5v inputs, but anything above 3.3v will return 1,023. The analog pins A10-A14, which cannot be used for digital input/output are not 5v tolerant. Note, the Teensy 3.1 is also a microprocessor (and uses modified Arduino libraries), and will not run Linux. PJRC Store
It might be simpler to include a 5v Arduino class machine with a small form factor (pro mini, nano, etc.) to do the 5v work, and then communicate with the Linux system via i2c (you will need a level converter for i2c). This assumes you only read your sensors i2c time scales (100kHz).
MichaelMeissner:
SixSixSevenSeven:
Only ARM chip I have ever seen with 5v tolerant inputs is the LPC1114 which is a microcontroller and certainly not linux capable.The Teensy 3.1 which uses the Freescale Cortex-M4, MK20DX256VLH7 has 5v tolerant inputs for digital pins. The analog pins that also support digital input/output, will take 5v inputs, but anything above 3.3v will return 1,023. The analog pins A10-A14, which cannot be used for digital input/output are not 5v tolerant. Note, the Teensy 3.1 is also a microprocessor (and uses modified Arduino libraries), and will not run Linux. PJRC Store
It might be simpler to include a 5v Arduino class machine with a small form factor (pro mini, nano, etc.) to do the 5v work, and then communicate with the Linux system via i2c (you will need a level converter for i2c). This assumes you only read your sensors i2c time scales (100kHz).
Didn't know the freescale m4 would do 5v input, useful info for future.
For 5v-3.3v i2c interaction there is an alternative. Pull the bus up to 3.3v. As devices only pull the bus to ground, the bus will never actually be exposed to 5v and yet most 5v devices will recognise 3.3v as a high.
devices only pull the bus to ground,
This is NOT generally true. It would apply to I2C, mostly.
If you are only building a few units, plunking down the $3 for a level converter might be a lot simpler. You do have problems for high speed protocols, whether the level converter is fast enough.
thanks for the advice everyone
the teensy looks like a great little product
i like the look of the pcduino - but i need to be able to run windows apps on it
is there something like the pcduino that will run windows ce ?